Method of manufacturing heat exchanger



Dec. 7, 1965 J. KARMAZIN 3,221,399

METHOD OF MANUFACTURING HEAT EXCHANGER Filed March 28, 1962 3 Sheets-Sheet 1.

m I) v/ c (cc a 14 I l 'NVENTOR. L 4? i :L Jill/ K477774227! W "fin Dec. 7, 1965 J. KARMAZIN 3,221,399

METHOD OF MANUFACTURING HEAT EXCHANGER Filed March 28, 1962 3 Sheets-Sheet 2 Zfi 'jd 4 INVENTIOR. 767177 K477714277? Dec. 7, 1965 J. KARMAZIN 3,221,399

METHOD OF MANUFACTURING HEAT EXCHANGER Filed March 28, 1962 3 Sheets-Sheet 5 Q INVENTOR.

J'o%77 A2 7' 7714,? 2 '71,

/ iiiaT- United States Patent 3,221,399 METHOD OF MANUFACTURING HEAT EXCHANGER John Karmazin, Karmazin Products Corporation, Wyandotte, Mich. Filed Mar. 28, 1962, Ser. No. 183,164 3 Claims. (Cl. 29157.3)

This invention relates to heat exchangers and to a method of manufacturing heat exchangers of the type having a plurality of conduits provided with heat radiating fins.

It is an object of the present invention to provide a method of manufacturing a heat exchanger which is relatively inexpensively and conveniently performed and which does not require the use of a brazing furnace.

It is another object of the present invention to provide a method of manufacturing heat exchangers of the above character wherein the conduits through which the refrigerant or other fluid is circulated may be made of one material and the heat radiating fins may be made of another material.

It is another object of the present invention to provide a method of manufacturing heat exchangers which results in the production of heat exchangers possessing superior strength and rigidity, long, useful lives and a high rate of heat transfer.

It is still another object of the present invention to provide a method of manufacturing heat exchangers as a result of which the conduits through which the fluid medium is circulated are completely covered by a protective layer of material to insulate and protect the conduits from the corrosive or destructive effect of the atmosphere in which the heat exchanger is used.

These and other objects of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings wherein:

FIGURE 1 is a perspective view of a heat exchanger made in accordance with the principles of the present invention;

FIG. 2 is a front elevational view of apparatus utilized in the carrying out of the method of the present invention, showing the heat exchanger of FIGURE 1 during its manufacture;

FIG. 3 is an enlarged fragmentary sectional view of a portion of the structure of FIG. 2, showing the relative positions of the parts prior to the compression of the stack by the apparatus of FIG. 2;

FIG. 4 shows the heat exchanger of FIG. 3 after the compression of the stack by the apparatus of FIG. 2; FIG. 5 after the compression of the stack.

FIG. 3 showing another form of the invention; and

FIG. 6 is an enlarged view of the structure shown in FIG. 5 after the compression of the stack.

Referring now to the drawings, the numeral 10 designates a heat exchanger composed of a plurality of conduits or tubes which are interconnected at their ends to form a continuous path for the flow of fluid through the heat exchanger. The tubes are provided with heat dissipating fins projecting laterally therefrom, thereby presenting a large surface area in contact with the air or other medium in which the heat exchanger is positioned.

The heat exchanger 10 is made up of a plurality of identical panels or sheets 12, each of which is substantially of flat planar shape over its major portion and is formed with a plurality of integral tubular projections 14 which taper radially inwardly toward their free ends. The projections 14 are disposed in identical locations on each of the sheets 12 so that the sheets may be arranged in parallel stacked relation with the projections of one sheet nested within the similarly located projections of the next adjacent sheet. The sheets 12 with their projections 14 may be formed by the method shown in my prior US. Patent No. 2,783,726 of March 5, 1957. The aligned nested projections 14 define passages extending perpendicular to the plane of the sheets 12 for the reception of tubes 16. The projections 14 surround and engage the outer diameter of the adjacent tube 16 which extends therethrough. The heat exchanger illustrated herein utilizes twelve separate tubes 16 arranged in two vertical rows of six each. However, it will be appreciated that any number of tubes could be utilized. It will be seen that the planar portions of the sheets 12 form heat radiating fins to enhance the rapid transfer of heat to or from the fluid circulated through the tubes 16.

The tubes 16 will be seen to project beyond the sheets 12 at each end of the heat exchanger and have their free ends enlarged, as indicated at 18, for the reception of U-shaped return members 20 and 22. The joints between the ends of the tubes 16 and the return members 20 and 22 are preferably individually soldered to seal the joints against the escape of fluid. The return members 20 and 22 are arranged to provide a sinuous path of flow for refrigerant through the heat exchanger from an inlet 21 to an outlet 23.

As shown in detail in FIGS. 3 and 4, each of the tubular projections 14 has a mouth 24 at the end thereof which is connected to the sheet 12 and a terminal portion 26 at its free end. The mouth 24 of each projection 14 defines an opening in its sheet 12 which is of a diameter somewhat greater than the outside diameter of the tubes 16, plus twice the thickness of the material of the tubular projections 14. The terminal portion 26 of the projections 14 possesses an inside diameter coincidental with the outside diameter of the tubes 16.

In the manufacture of the heat exchanger 10, a plurality of sheets 12 are stacked together so that their projections are arranged in nested relationship. In initially stacking the sheets 12, no substantial degree of pressure is applied to the stack in a direction normal to the plane of the sheets 12. In this position, the terminal portion 26 of each projection assumes its normal diameter as originally formed. A tube 16 is then inserted into each of the aligned rows of projections 14. In so doing, the outside diameter of each tube 16 will engage the terminal portion 26 of each projection 14. However, the fit is such that the tube 16 may be relatively freely slid down the length of the projections 14. The assembly consisting of the sheets 12 and tubes 16 is then positioned in the apparatus shown in FIG. 2. The apparatus of FIG. 2. is utilized to apply a compressive force to the stack in a direction parallel to the length of the tubes 16. This compression of the stack, which moves the sheets 12 closer together, is effective to provide tight fitting engagement between the terminal portions 26 of the projections 14 and the outside diameter of the tubes 16. Portions of the pro- 3,221,399 Patented Dec. 7, 1965 jections14 are distorted into conforming binding engagement with the outer diameter of the adjacent tube 16. The distorted areas are indicated at 28 with respect to the sheet 12 at one end of the stack and at 30 with respect to the projections of the remaining sheets 12. The compression of the stack moves the sheets 12 closer to one another and, in so doing, the inside diameter of each projection 14 serves to force the projection 14 inserted thereinto in a radially inward direction, causing it to bind against the outside diameter of the adjacent tube 16 and form a distorted projection portion 30.

The apparatus of FIG. 2 consists of a stationary bottom die member 32 and an upper movable compression plate or die member 34 carried by the piston rod 36 of a power cylinder 38. A bracket 40 interconnects the piston rod 36-, and the die; plate 34. The lower die member 32 is provided with a plurality of annular grooves or cavities 42 which receive the lower ends of the tubes 16 and locate the tubes 16 in both a vertical and a horizontal direction. The grooves 42 are of a width slightly greater than the wall thickness of the tubes 16, permitting the reception of the projections 14 of the lowermost sheet 12 and serving to distort said projections against the outer diameter of their tubes 16, as indicated at 28. The upper die member 34 is suitably apertured to permit the upper ends of the tubes 16 to move freely therethrough. The upper die member 34 flatly engages the uppermost of the sheets 12 and, upon operation of the cylinder 38, applies a downward force compressing the stack in a direction normal to the plane of the sheets 12. As the die member 34 is forced downwardly, each of the sheets 12 moves downwardly relative to the tubes '16 and the terminal portion 26 of each of the projections 14 is forced radially inward by virtue of the successively smaller diameter of the inner surface of the projection 14 into which it is thrust. The projection portions 30 thus bindingly engage the outside diameter of the tubes 16 and securely locate the sheets 12 in position on the tubes 16 and eliminate the necessity of brazing or otherwise bonding the sheets .12 to the tubes 16.

In practice, the tubes 16 are desirably formed from copper, as are thereturn members 20 and 22. The sheets 12. may be'formed from aluminum, steel or other less expensive material; Thus, the overall cost of the heat exchanger is reduced compared to a heat exchanger formed entirely from copper. In the event that sheets of aluminum or steel disintegrate or erode as a result of salt-laden air or other corrosive atmosphere in which the heat exchanger is used, the copper tubes 16 will continue to provide a sealed enclosure for the refrigerant, preventing the escape of the refrigerant to the atmosphere. Furthermore, the projections 14 completely surround the tubes 16 and protect the tubes 16 from the corrosive effects of the surrounding atmosphere.

FIGS. and 6 illustrate the use of the present invention in the formation of a somewhat modified heat exchanger, wherein aplurality of sheets 44 are provided with similarly located tubular projections 46. The sheets 44 are arranged in stacked relationship with the projections 46 thereof nested within one another, and defining aligned passages for the reception of tubes 48. The projections 46 have terminal portions 52 at their free ends engaging the outside diameter of the tubes 48 and mouths 50 at the ends thereof connected to the sheets 44, The mouths 50 define openings in the sheets 44 of a diameter equal to the outside diameter of the tubes 48, plus twice the wall thickness of the projections 46. In the manufacture of this heat exchanger, after the sheets 44 have been stacked together and the tubes 48 positioned through the projections 46, the entire stack is compressed with a force suflicient to cause the projections 46 to enter the space between the outside diameter of the adjacent tube 48 and the inside diameter of the next adjacent projection 46. The force applied is sufficient not only to radially inwardly deflect the terminal portion of each projection 46 but to radially outwardly expand that portion of each projection 46 adjacent its mouth 50. The extent of compression is such as to locate the terminal portion 52 of each projection substantially in line with the plane of the second sheet 44 away from the sheet 44 to which it is connected. An annular shoulder 54 is formed on each projection 46 at the next adjacent sheet 44 to the sheet to which it is attached. It will thus be seen that the entire outside diameter of that portion of each tube 48 within the area of the sheets 12 is conformably engaged by the projections 46. Such large area contact enhances the transfer of heat from the tubes 48 to the sheets 44.

The angle of taper of the tubular projections of the sheets illustrated herein is between 2 and 3 degrees. It is to be understood, however, that a variety of angles of taper may be selected for the projections 14 or 46 with advantageous results.

While it will be apparent that the preferred embodiments herein illustrated are well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. The method of manufacturing a heat exchanger which includes stacking a plurality of sheets of material having integral tapered tubular projections with the projections of adjacent sheets arranged in nested relationship, positioning a tube within a row of nested projections of said sheets, the outer diameter of said tube being substantially coincidental with the inner diameter of the terminal portions of said projections, and compressing the stack longitudinally of the tube to cause the ends of the projections of said row to deflect radially inwardly into gripping engagement with the outer diameter of the tube and to cause most of said projections to extend along said tube substantially the entire distance between a next adjacent pair of sheets, whereby said tube isenclosed by a double layer of said projections for the major portion of its length.

2. The method of manufacturing a heat exchanger which includes providing a plurality of identical sheets of material having integral uniformly tapered tubular projections, stacking said sheets of material with the projections thereof arranged in nested relationship, positioning tubes within the aligned rows of nested projections of said sheets, said tubes having an outside diameter of a size suflicient to provide a space between their outer diameters and the ends of said tubular projections adjacent the sheets to which they are connected which is equal to twice the wall thicknesses of the tubular projections, and compressing the sta-ck longitudinally of the tubes to cause the portionsof said projections adjacent the free ends thereof to deflect radially inwardly into binding engagement with the outside diameter of the adjacent tube, to cause the portions of said projections adjacent the sheet to which they are connected to deflect radially outwardly to accommodate the projections received therein and to :cause most of said projections to extend along said tube substantially the entire distance between a next adjacent pair of sheets, whereby said tube is enclosed by a double layer of said projections for the major portion of its length.

3. The method of manufacturing a heat exchanger which includes stacking a plurality of sheets of material having integral tapered tubular projections with the projections of adjacent sheets arranged in nested relationship, said projections having an angle of taper of between 2 and 3 degrees positioning a tube within a row of said nested projections, said tube having an outside diameter which is coincident with the inside diameter of the small diameter of the ends of said tubular projections and which is smaller than the inside diameter of the large diameter ends of said tubular projections by an amount substantially equal to twice the wall thickness of said tubular project-ions, compressing the stack in a direction longitudinally of the tube to cause the ends of the projections of said row to deform radially inwardly into binding engagement with the outer diameter of said tube and to 5 6 cause most of said projections to extend along said tube 1,907,036 5/1933 Belleau 165182 XR substantially the entire distance between a next adjacent 2,032,365 3/1936 Karmazin. pair of sheets, whereby said tube is enclosed by a double 2,557,760 6/ 1951 Powell et a1 165-182 layer of said projections for the major portion of its 2,743,512 5/1956 Moyer 29-1573 XR length, and interconnecting the ends of adjacent tubes to 5 2,788,195 4/1957 Karmazin 29157.3 XR provide a continuous path for the flow of fluid through the FOREIGN PATENTS heat exchanger.

493,986 10/1938 Great Britain.

References Cited by the Examiner UNITED STATES PATENTS 1,634,110 6/1927 McIntyre 165-482 10 WHITMORE A. WILTZ, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,221,399 December 7, 1965 John Karmazin It is hereby certified that error appears in the above numbered pat ent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 52, for "FIG. 5 after the compression of the stack." read FIG. 5 is a view of structure similarly illustrated in as the beginning of a new paragraph.

Signed and sealed this 20th day of September 1966.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. THE METHOD OF MANUFACTURING A HEAT EXCHANGER WHICH INCLUDES STACKING A PLURALITY OF SHEETS OF MATERIAL HAVING INTEGRAL TAPERED TUBULAR PROJECTIONS WITH THE PROJECTIONS OF ADJACENT SHEETS ARRANGED IN NESTED RELATIONSHIP, POSITIONING A TUBE WITHIN A ROW OF NESTED PROJECTIONS OF SAID SHEETS, THE OUTER DIAMETER OF SAID TUBE BEING SUBSTANTIALLY COINCIDENTAL WITH THE INNER DIAMETER OF THE TERMINAL PORTIONS OF SAID PROJECTIONS, AND COMPRESSING THE STACK LONGITUDINALLY OF THE TUBE TO CAUSE THE ENDS OF THE PROJECTIONS OF SAID ROW TO DEFLECT RADIALLY INWARDLY INTO GRIPPING ENGAGEMENT WITH THE OUTER DIAMETER OF THE TUBE AND TO CAUSE MOST OF SAID PROJECTIONS TO EXTEND ALONG SAID TUBE SUBSTANTIALLY THE ENTIRE DISTANCE BETWEN A NEXT ADJACENT PAIR OF SHEETS, WHEREBY SAID TUBE IS ENCLOSED BY A DOUBLE LAYER OF SAID PROJECTIONS FOR THE MAJOR PORTION OF ITS LENGTH. 